A series of cats were subjected to left MCAO for 1 hour. During ischemia rCBF fell to less than 11 ml/100g/min. CEI rose about 211%. After release of occlusion, CEI decreased to pre-ischemic levels but a second rise of about 176% within 15 hrs of release from MCAO followed. During this late rise the rCBF was 54(plus/minus)5ml/100gm/min. The second rise was also observed in cats in which the MCAO was permanently occluded (rCBF = less than 1 ml/100gm/min. The secondary rise is thought to be related to brain compression induced by brain edema.